Recently, frequency spectrum for mobile communication has been widened significantly. However, antenna volume in mobile devices, such as smartphones and computer laptops/tablets, has not been increased to accommodate the widened bandwidth requirement. Typically, one frequency band is used at a time for communications at the mobile device. The device's antenna can be designed in such a way that it is adaptive to the frequency being used. At the mobile device, the resonant frequency of an antenna can be adjusted by the length of the antenna element as well as the coupling between the antenna element and the printed circuit board (PCB). However, due to limitation in available space for antenna design in mobile devices, the option of increasing the length of antenna is limited. Thus, there is a need for an efficient and relatively simple to implement antenna design and operation method to adjust or add frequency bands or communication frequencies at mobile devices using the available limited antenna volume or size.